Thermal window



H. D. PEETZ THERMAL WINDOW Filed Sept. 11, 1967 Oct. 1910 6 x k M ART mR P INVENTOR.

HA N5 0/6 rm PEEI'Z ATTOR Y3 vBY United States Patent Int. Cl. rrosb3/06 US. Cl. 219-522 4 Claims ABSTRACT OF THE DISCLOSURE A thermalwindow is provided with a thermal grid of which the current-carrying busis out of contact with the gasket which mounts the pane.

This invention relates to thermal windows the general nature of which isset forth in French Pat. 1,464,585. In such windows a thermal grid isprovided which has linear thermal strips extending betweencurrent-carrying buses. The buses are usually of one piece with thestrips. The grids are frequently made by forming thin resistor filamentsand bus bands in the plastic layer between two sheets of glass, of thetype normally used for automobile Windshields in the United States, orby deposition on the surface of tempered glass windows. The generalconstruction of such windows, as viewed in section, is shown in FIG. 6of the French patent, which is reproduced herein as our FIG. 1. In thatfigure a pane 41 of tempered glass bears on its surface a thermal gridwhich is composed of spaced parallel strips or filaments 46 connected attheir ends to bus bands 6, which extend along opposite edges of thepane. A contact 43 brings current from a lead 45 to the bus band, whichdistributes it to the strips, it passes through the strips to the otherbus and returns to its source. The pane is set in a rubber gasket 44,which covers the bus bands.

Although this construction has great merit it has been discovered that,after a certain time, the efficiency of the thermal grid decreases tothe point that the fogging or icing of the window, which it is designedto prevent, still occurs. It also appears that the resistance of thegrid increases with time so that the bands most remote from the inputcontact no longer function properly. There have also been instances ofdisengagement between the buses and the strips for which the conditionsof use do not offer an explanation.

It is an object of this invention to discover the reason for thesedifiiculties and to overcome them. Although the reason for the decreasein efliciency of such grids is not yet fully understood, the objectionshave been overcome by the present invention, so that thermal windowsconstructed as herein provided have a lifetime of full efiiciency.

The objects of the invention have been accomplished generally speakingby a thermal window having a pane of glass, a thermal grid mounted incontact therewith, the thermal grid having thermal strips extendingbetween current-carrying bus means, the pane being mounted in gasketmeans, and the bus means having current carrying portions out of contactwith the gasket means.

A preferred form of the invention is illustrated in the drawing, ofwhich:

FIG. 1 is a substantial copy of FIG. 6 of the aforesaid French patent;and

FIG. 2 is a perspective view, partly in section, of a preferred form ofthe invention illustrating a thermal window carrying a thermal gridconstructed in accordance with the principles of the invention.

In FIG. 2 the numeral 1 indicates a pane of tempered 3,532,858 PatentedOct. 6, 1970 Ice glass; numerals 2, 3 indicate a thermal grid of someuseful type, for instance of the type described in the French patent,which is in contact with the pane, part 3 being one of the bus bands orbars between which the parallel resistance strips 2 extend. Aflixed tothe band 3 is an input contact 4, 5 which is to be connected to acurrentcarrying lead, not shown. A channeled gasket 6, usually rubber,or rubbery material, that is to say some form of non-conductive plastic,seals the border of the pane and makes it weatherproof. The type ofthermal window shown is of the sort used as automobile rear windows. Thedistance B is the total width of the current-carrying bus, and the widthA indicates an extension of the bus beyond the limits of the gasket.

According to a characteristic of the invention each bus band has a widthgreater than the part of it which is covered by the rubber gasket, whichis, in effect, to say that each bus band has a part out of contact withthe gasket, the part being adequate in itself to carry the current toand from the resistor strips which connect the two bands. In accordancewith this principle it is desirable that the connection between thesource of current and the bus band should furnish a conductive line freeof the gasket.

In this novel construction the strips do not break away from the bands,substantially equal current is delivered to all bands by the busesregardless of their distances from the contacts, the increase ofresistance with age does not occur, and a lifetime of uniform service isassured. As the ordinary gasket is non-conductive by test and bymaterial, it is apparent that an unusual phenomenon is present, theprecise nature of which is unknown. However, it may be assumed that,although the gasket is non-conductive, it in some way inhibits the flowof current in the part of the bus with which it is in contact, but thatthis inhibition does not extend to parts of the bus which it does nottouch, even though the two parts of the bus are unitary.

The advantages of the invention have been in part stated hereinabove andin part reside in the accomplishment of the objects of the invention.

The term strip in the claims is to be interpreted as including wires,ribbons, filaments and rods.

As many apparently widely different embodiments of the present inventionmay be made without departing from the spirit and scope thereof, it isto be understood that the invention is not limited to the specificembodiments.

What is claimed is:

1. In a thermal window, a mounting gasket of resilient rubberydielectric material having a channel therein extending along itslongitudinal dimension, to define spaced side walls, a pane of glasshaving an edge fitting said channel, a thermal grid comprising aplurality of electrical conductor strips extending in spaced relationpermitting visibility through the pane over and in contact with saidpane, in a direction generally transverse of said channel, and a bus barelectrically connecting the ends of said strips and interposed betweensaid pane and one side wall of said channel, said bus bar having an edgeportion exposed to the atmosphere extending longitudinally along saidgasket out of contact therewith, said edge portion being adequate initself to carry the electrical current passing through the thermal grid,the glass pane, the bus bar and the mounting gasket being in direct andtight contact with each other.

2. The thermal window of claim 1, said bus bar being a flat ribbon ofmetal, said exposed portion thereof having a longitudinal edge generallyparallel with said gasket, the ends of said strips merging into saidedge.

3. The thermal window of claim 2, and an electrical input contact fixedwith said bus bar over at least a portion of said exposed portionthereof.

4. In a thermal window, a mounting gasket of resilient rubberydielectric material having a channel therein extending along itslongitudinal dimension, to define spaced side Walls, a pane of glasshaving an edge fitting said channel, a thermal grid comprising aplurality of electrical conductor strips extending in spaced relationover and in contact with said pane, in a direction generally transverseof said channel, and a bus bar electrically connecting the ends of saidstrips and interposed between said pane and one side wall of saidchannel, said bus bar having a free exposed surface area extendinglongitudinally along said gasket, out of contact therewith, said bus barbeing a fiat ribbon of metal, said exposed area thereof defining alongitudinal edge generally parallel with said gasket, the ends of saidstrips merging into said edge, and an electrical input contact fixedwith said bus bar over at least a portion of said exposed area thereof,said contact being flat and extending into said channel between said oneside wall thereof and said bus bar, the pane, the bus band, the

flat contact, and the mounting gasket being in direct and tight contactwith each other.

References Cited UNITED STATES PATENTS 2,513,993 7/1950 Burton 219-202 X2,977,450 3/1961 Boicey 219-54 1 3,288,983 11/1966 Lear 219522 3,315,2174/1967 Bird 339-176 2,625,640 1/1953 Gaiser et al. 219522 FOREIGNPATENTS 1,264,475 5/1961 France. 1,464,585 11/1966 France.

VOLODYMYR Y. MAYEWSKY, Primary Examiner U.S. Cl. X.R.

